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Jne 20, 1933. A. H. TAYLR Re. 18,877

RECEIVER OF HIGH FREQUENCY ELECTRICAL SIGNALS original Filed May 29, 1923 iL A @www gwn/Genion Reissued June 20, 1933 lTUNITED STATES ALBERT H. TAYLOR, OF WASHING-TON, DISTRICT F COLUMBIA RECEIVER OF HIGH FREQUENCY- ELECTRICAL SIGNALS 4Original No. 1,489,287, dated April 8, 1924, Serial No. 642,354, led May 29, 1923. Application for reissue filed January 20, 1925.

` fectively isolated lfrom the tunable circuits of an associated receiver and vacuum tube circuits.

Inthis particular adaptation of my invention one object is the multiple reception of such signals without disturbing reactions between the several tunable receivers connected to the one collector or between any of the parts of any one receiver and the antenna.

I utilize my invention by adapting well known forms of'radio receiving systems including tuned'vacunm tube amplifier and detector circuits to a special mode of association with an antenna system.

An effective amplier and detector combination in a high frequency signal receiving system comprising a high'frequency amplifier in advance of a detecting element was first disclosed by Schloemilch and von Bronk in U. S. Patent 1,087,892 of February 17, 1914. "0 Alexanderson in U. S. Patent 1,173,079 of vFebruary 22, 1916, and Bucher in Practical Wireless Telegraphy, 1917 edition, page 284, disclosed a like system having a' cascade series of similar resonant circuits with interposed three-electrode vacuum tubes; while pages 54 to59, Wireless Age for lApril 1923, and pages 67 to 71 of The Wireless World and Radio Review of April 21, 1923, cover in detail a number of features of such systems including the usual practice of using like fixed coils and rotary tuning condensers in each of the several tuning circuits whereby like movements of the condenser' rotary elements produce like capacity or tuning i change in the` several circuits. These systems employ a high order of precision in thematter of selectivity, and therefore function to better advantage in the maintenance vof the intended precise tuning when employed with myarrangement whereby any variations -of Serial No. 3,705.

reactance in the antenna are not disturbingly reflected into the tuning system.

My improvement'is of particular value on shipboard where it may be desirable to re ceive a large number of signals simultane! o usly, and the facilities for rigging a number of antennae are limited, and in like adaptations wher-e the reaction isolating features oer `advantageous immunity from reactance variations. i

My invention will be best understood by reference to the accompanying drawing, the ligure illustrating its use for the reception of radio signals. The figure is a schematic illustration of an arrangement permitting the connection of a plurality of selective receivers to an isolated antenna.

In the figure Alis an antenna having high resistance in series therewith. The thermionic vacuum tube V has its grid circuit con-y nected between two points in this resistance. The plate circuit of this vacuum tube contains a switch S which, in its lower position, connects to the tunable high frequency circuit having inductance L1 and variable capacity C1 in parallel relation. I find it preferable to make the ratio of inductance to capacity in this circuit large. There is also included in this circuit a device J which I term a rejector. It comprises a very low inductance ele-ment having very low resistance, usually being one or more turns of very heavy copper strip or wire and a large capacity condenser constructed to' have small resistance, the condenser being made variable in ord-er to permit of tuning the rejector element t-o the desired wave length. Shunted around the rejector is'a tunable circuit containing inductance L2 Vand variable capacity C2 in series.

A receiver of the character hereinbefore referred to is associated with this last named circuit usu'ally through a tunable circuit, usually constituting the first tuned radio frequency stage of the radio frequency amplitier of the receiver, and'containing inductance Laand variable condenser C3. B1 is a source of current for heating the filament of the vacuum tube V and B2 is a source of current for the plate circuit of this vacuum tube. These same sources may be used in connec-` connections can be made without derogatory infiuences on the tuning system of the receiver is certain from analyzing the inherent actions and reactions of a system connected 1n accordance w1th myv invention as follows:

. The grid-to-plate capacity of the tube V is the only reactive coupling element between the antenna. system on the one side of theV tube and the elements of the tuning system on the other side of the tube. Since the grid-toplate capacity of such tubes is exceedingly Y small, 6 to 8 Inicro-micro-farads being usual,

the eHective reactive coupling between the two parts of the system is accordingly practically negligible in proportion to the reactive effects and variations of them in the tuning elements going to make up the tuning system and in the physical elements going to make up the antenna system.

For example, alterations may be made in the antenna system, or in the connections thereto, which change the effective capacity of the antenna system many micro-microfarads without this change in capacity reaction being reflected into the tuning circuits Vin the output system of the tube V, or in the input system of the radio frequency amplifier connected to this output circuit.

In other words, the mutual reaction by way of the grid-to-plate capacity of the tube inits coupling effect between the antenna system on the one side of the tube-and thetuning system onthe other side of the tube is such that it qualifies under the term of very loose coupling. v v

As a result of this loose coupling the tuning condensers (32,703, etc. in the circuits of the vacuum tube amplifier system tune to definite dial indications from one wave length to another under all conditions of the anten-V na system, and no change in the reactive conditions of the antenna will alter the dial readings-of the condensers or tuning devices that may be employed succeeding tube V or in succeeding stages `of a multi-stage radio frequency amplifier. Where theY tuning circuits are alike, as in some of the examples of the prior art, the dial settings will be alike in tuning from one wave length to another.

I term the vacuum tube V a coupling tube because it couples the collector to the selec- 55 tive circuits and receiverr as illustratedA and by tuning the inductance ymits further selectivity, the desired signal at the same time prevents reactive interaction between them or between selective circuits of different receiving systems connected to the antenna.

The operation of the system is as follows: Assuming that a llllmber of signals of differentY frequencies are being collected on the antenna A, the desired si al is selected out -1 or condenser C1 which admits vthis particular signal to the circuit containing these elements. However, as other signals cannot be entirely excluded from this circuit, thetuning of they rejector J to the frequency lof the desired signal per- S0 being accepted by the reject-or and all other signals being rejected or by-passed by the low induct-ance element of this device. rEhe desired signal is then passedonjtothe receiver through the tuned circuit containing inductance L2 and capacity C2, any residual undesired signal being excluded from` this circuit through being out ofvtune with it.

To aid in picking` up signals the switch S is thrown into the up position, in; which itv eliminates the intermediate selective circuit-s, connecting the coupling tube directly to the circuit containing inductance L2 and Vcapacity C2. This arrangement not being so selective as the rejector circuit permitsy of the signal being. picked up promptly and adjusting the receivercontaining inductance L3 and capacity Cato the desired frequency. Having found the desired signalf and adjusted the receiving circuits, the switch Si 100 may be Ythrownto the down,.position connecting in the intermediate,selective4 circuitsand these are then tuned until the desired signal is brought in and the undesired signals excluded. Y The amplifier and detector indicatedl in the gure may includeva three electrode vacuum tube amplifier and contactj Vdetector which may be substituted by a vacuumtube or other suitable detector. rlhe receiverl mayv .110

be of the. tuned radiofrequency form, an example ofLwhich-is illustrated at; page 2,84-v of Practical Wireless ',Eelegraphy, 191'( edition, by Bucher, and has a ,tunableinput circuit comprising tuning condenser C3 and coil L31 115 coupling tube .shall be independent in their LI 130 tuning functions of the electrical constants of the untuned antenna or labsorption struc ture.

While I have described my invention in connection with particular practical embodiments thereof, no limitations are intended by reason of the selection of the particular embodiments for explanatory purposes, the

invention being one of general and broad application.

Having described my invention I claim:

1. In a system for the reception of hlgh frequency electrical signals the combination of a collector circuit having a high resistance in series therewith, a coupling thermionic vacuum tube'having its input circuit connected between two points in said resistance and an output circuit having in series therewith a tunable circuit containing variable constants in parallel relation, a tunable rejector circuit in series relation within said tunable circuit, a tunable circuit in parallel relation to said rejector, and a receiver associated with said last tunable circuit.

2. In a system for the reception of high frequency electrical signals the combination of a collector circuit having a high resistance in series therewith, and a plurality of `receivers connected theretoeach through the following elements: a coupling thermionic vacuum tube having its input circuit connected between two points in said resistance and an output circuit having in series therewith Ya tunable circuit containing variable constants in parallel relation, a tunable rejector circuit in series relation within said tunable circuit,

and a tunable circuit in parallel relation toV said rejector.

3. In a system for the reception of high frequency electrical signals, the combination of a collector circuit, a thermionic vacuum tube having its input circuit associated with said collector circuit to derive signal energy therefrom, and an output circuit for said tube having in series therewith a tunable circuit containing variable constants in parallel relation, a tunable rejector circuit in series relation within said tunable circuit, a tunable crcuit in parallel relation to said rejector, and a receiver associated with said last tunable circuit.

4. A radio receiving system comprising the combination with an absorption structure, of a plurality of circuits in cascade, means for tuning each of said circuits, and a three-electrode vacuum tube interposed between the first of said tuned circuits and said absorption structure, the input of said tube and said absorption structure constitutingl an input system the magnitudes of whose inductance and capacity are substantially constant and so related to said tunable circuits as to permit equal movements of their tuning devices in adjusting from resonance for onewave length to resonance for another Wave length, characterized by the fact that the output circuit of the three-electrode vacuum tube interposed between the `first of said tuned circuits and said absorption structure is substantially devoid of fluctuating or alternating current except current of radio frequency.

5. A' radio receiving system comprising the combination with an absorption structure, of a plurality of circuits in cascade,

means for tuning each of said circuits, and a three-electrode vacuum tube having its output operatively related to the first of said tuned circuits and having its input electrodes non-reactively conductively connected with said absorption structure, said absorption structure and the input of said tube constituting an input system the magnitudes of whose inductance and capacity are substantiaily constant and so related to said tunable circuits as to permit equal movements of their tuning devices in adjusting from resonance for one wave length to resonance for another wave length, characterized by the fact that the output circuit of said threeelectrode vacuum tube is substantially devoid of fluctuating or alternating current eX- rcept current of radio frequency.

6. In a signal receiving system comprising an absorption structure and a receiver including a plurality of adjustable circuits for selective tuning, the method of rendering tuning variations of the electrical constants of said adjustable circuits independent of the electrical characteristics of said absorption structure which consists of aperiodically transferring and thermionically relaying the energy from said absorption structure to said adjustable circuits.

* ALBERT H. TAYLOR. 

